The present invention relates generally to internal combustion engines, and particularly to an apparatus for electronically limiting the revolution rate of internal combustion engines.
Internal combustion engines are designed to operate over certain speed ranges, which are generally expressed in revolutions per minute (RPM). To insure that these engines are not operated above the maximum rated speed, various techniques have been employed for mechanically limiting the speed of the engine. In one such technique, a mechanical linkage is employed to limit or block the travel of the throttle linkage beyond a certain point. Although mechanical linkages are effective for this purpose, it will be appreciated that these mechanical linkages can become relatively complex when more than one maximum speed is desirable. For example, in a motor or power plant which is designed to operate in different operation states, such as drive states (e.g., forward, neutral or reverse), it is generally advantageous to permit a different maximum speed for each drive speed. Thus, it will be appreciated that it is typically desirable to have a lower maximum speed for the engine when the power plant is in neutral (or other no load condition) than when the power plant is in forward, and so forth.
It is, therefore, a principal object of this invention to provide an improved apparatus and method for limiting the speed of an internal combustion engine which does not depend upon mechanical linkages and is also capable of permitting a plurality of maximum speeds for the engine.
It is another object of the present invention to provide an improved apparatus and method for electronically limiting the revolution rate of an internal combustion engine through an interaction with the ignition system for the engine.
It is a further object of the present invention to provide an improved electronic revolution rate limiting apparatus and method for limiting the engine speed when the power plant is shifted from one drive state to another.
It is an additional object of the present invention to provide an improved electronic revolution rate limiting apparatus which will remain accurate and not be adversely affected by engine temperature and/or power supply voltage variations.
It is yet another object of the present invention to provide an improved electronic revolution rate limiting apparatus which will permit the operator to set the maximum revolution rates.